EGU22-865
https://doi.org/10.5194/egusphere-egu22-865
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Understanding salt marsh resilience to changes in external disturbance

Natascia Pannozzo1, Rachel Smedley1, Richard Chiverrell1, Iacopo Carnacina2, and Nicoletta Leonardi1
Natascia Pannozzo et al.
  • 1University of Liverpool, School of Environmental Sciences, Geography and Planning, United Kingdom of Great Britain – England, Scotland, Wales
  • 2Liverpool John Moores University, School of Civil Engineering and Built Environment, Civil Engineering, United Kingdom of Great Britain – England, Scotland, Wales

Salt marshes are valuable ecosystems that provide numerous services and act as natural coastal defences by buffering storm waves and stabilising sediments. However, it is not clear whether they will be able to retain their resilience with accelerating rate in sea-level rise, possible increases in storm intensity, increasing land reclamation and changes in sediment supply. The current paradigm is that a positive sediment budget supports the survival and accretion of salt marshes while a negative sediment budget causes marsh degradation. Here we present the results of two studies (Pannozzo et al., 2021a,b; Pannozzo et al., 2021c) that used an integration of modelling and paleoenvironmental analysis and a sediment budget approach to investigate the resilience of estuaries and salt marshes to projected rise in sea-level, possible increases in storm activity, existing anthropogenic disturbance and natural sediment supply. The studies were conducted using the Ribble Estuary - North-West England - as a test case, the hydrodynamic model Delft3D to simulate the estuary morpho-dynamics under selected scenarios, and optically stimulated luminescence (OSL), geochemistry and particle size distribution analysis to reconstruct the past evolution and adaptation of the estuary morphology. Pannozzo et al. (2021a,b) showed that sea-level rise threatens estuary and marsh stability by promoting ebb dominance and triggering a net export of sediment. Conversely, storm surges aid the resilience of the system by promoting flood dominance and triggering a net import of sediment and have the potential to counteract the negative impact of sea-level rise by masking its effects on the sediment budget. Pannozzo et al. (2021c) showed that the addition of embankments can further promote ebb dominance in the system and intensify sediment export, further threatening marsh stability. This latest effect, however, becomes negligible with high natural sediment supply to the system.

References

Pannozzo N., Leonardi N., Carnacina I., Smedley R., 2021. Salt marsh resilience to sea-level rise and increased storm intensity. Geomorphology, 389 (4): 107825.

Pannozzo N., Leonardi N., Carnacina I., Smedley R., 2021. Dataset of results from numerical simulations of increased storm intensity in an estuarine salt marsh system. Data in Brief, 38 (6): 107336.

Pannozzo N., Smedley R., Chiverrell R., Carnacina I., Leonardi N., 2021. Influence of sediment availability and embankment construction on salt marsh resilience to sea-level rise. Journal of Geophysical Research: Earth Surface, In review.

How to cite: Pannozzo, N., Smedley, R., Chiverrell, R., Carnacina, I., and Leonardi, N.: Understanding salt marsh resilience to changes in external disturbance, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-865, https://doi.org/10.5194/egusphere-egu22-865, 2022.

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